The present invention relates to touch screens, and in particular relates to a capacitive touch screen.
In recent years, there has been an increase in demand for electronic devices, such as personal digital assistants (PDAs), mobile phones, and information appliances. To facilitate the users' input, many electronic devices employ touch panels as inputting devices.
Referring to FIG. 1, a conventional touch screen is shown. The touch screen includes a liquid crystal panel 1c, a touch panel 5, and an adhesive layer 6 between the liquid crystal panel 1c and the touch panel 5.
The touch panel 5 includes a glass plate 51, a first circuit layer 52, a transparent dielectric layer 54, a second circuit layer 53 and a transparent over coat 55 in the above-mentioned order from an outer surface of the touch screen. The first circuit layer 52 and the second circuit layer 53 can be made of indium-tin oxide (ITO). The transparent over coat 55 is dielectric, which is connected to the adhesive layer 6. The transparent over coat 55 is used for preventing the second circuit layer 53 from being damaged/scratched. The transparent over coat 55 can be made of silicon nitride or silicon dioxide.
The liquid crystal panel 1c includes a liquid crystal layer 15c, an upper glass plate 11c, an upper transparent conductive layer 12c, a lower glass plate 13c, a lower transparent conductive layer 14c, an upper polarizing plate 16c and a lower polarizing plate 17c. The upper transparent conductive layer 12c, the upper glass plate 11c and the upper polarizing plate 16c are deposed on the liquid crystal layer 15c in the above-mentioned order, and the upper polarizing plate 16c is connected to the adhesive layer 6. The lower transparent conductive layer 14c, the lower glass plate 13c and the lower polarizing plate 17c are positioned under the liquid crystal layer 15c in the above-mentioned order.
By a pen or a finger pressing at images or letter icons generated from the liquid crystal panel 1c on the outer surface of the touch screen, the user can input signals into the touch screen.
Generally, in a process of manufacturing the touch screen, the touch panel 5 and the liquid crystal panel 1c are made separately at first, and then the touch panel 5 and the liquid crystal panel 1c are assembled together. However, the process of assembling the touch panel 5 and the liquid crystal panel 1c requires high precision and costs time. In addition, the touch screen has a relatively high thickness.
What is needed, therefore, is a new touch screen that can overcome the above-mentioned shortcomings.